The Pipe Organ - Church Music
In church music, the organ is perhaps the first instrument to be considered. In 951, Elfeg, the Bishop of Winchester had built in his cathedral a great organ which had four hundred pipes and twenty-six pairs of bellows, to manage which seventy strong men were necessary.

The Pipe Organ Construction
An extract from an anonymous manuscript of the tenth century, in which the author gives directions for a set of organ pipes details the following instructions:

 "Take first, ten pipes of a proper dimension and of equal length and size. Divide the first pipe into nine parts; eight of these will be the length of the second. Dividing the length of this again into nine parts, eight of these will be the proper length of the third; dividing the first pipe into four parts, three of them will be the length of the fourth; taking the first pipe as three parts, two of them will be the length of the fifth; eight-ninths of this again will give the proper length of the sixth; eight-ninths of this, the length of the seventh; one-half the first, the length of the eighth, or octave."

The early pipe organs were furnished with slides which the organist pulled out when he wished to make a pipe speak, and pushed back to check its utterance. The date of the invention of the valve is uncertain, but it must have been about as soon as the power of the instrument was increased by the addition of the second or third stop. The earliest chromatic keyboards known are those in the pipe organ erected at Halberstadt cathedral in 1361. This pipe organ had twenty-two keys, fourteen diatonics and eight chromatics, extending from B natural up to A; and twenty bellows blown by ten men.